Radio tuner



Oct. 28, 1941. E. L. BARRETT 2,260,429

RADIO TUNER Filed May 21, 1938 a Sheets-Sheet 1 Oct. 28, 1941. E. 1.. BARRETT RADIO TUNER Filed May 21, 1938 s Sheets-Sheet 2 Oct. 28 1941. E. L. BARRETT 2,260,429

RADIO TUNER Filed May 21, 1938 5 Sheets-Sheet 3 I c/lT-rowsys Patentecl Oct. 28, 1941 UNITED STATESVPATENT OFFICE Edward L. Barrett, La Grange, Ill assignor to Utah Radio Products Company, Chicago, 111.,

a corporation of Illinois Application May 21, 1938, Serial No. 209,253

6 Claims. (CI. 7410) The invention relates to tuners for radio receivers and more particularly to tuners of the socalled station selector type which are adapted to position the tuning element of an associated radio receiver in such manner as to condition the same for the reception of signals from any selected one of a predetermined series of broadcasting stations. In such tuners a separate actuator is provided for each station tuning position and it is only necessary for the operator to select and move the actuator corresponding to the desired station as distinguished, for example, from the conventional dial type tuning device with which the tuning adjustment of the receiver is varied manually throughout a broad range until the frequency indicator dial shows the receiver to be tuned for the frequency of the signals from the selected station. Furthermore, the tuner herein contemplated is of a general type sometimes designated as mechanical. In such a mechanical tuner, all ofthe power required for moving the receiver tuning element is derived from the movable actuators in contrast with the arrangement in so-Called electric tuners in which the tuning element is driven directly by an electric motor controlled in its extent of movement so as to stop the tuning element in different station tuning positionsby, for example, an apparatus such as that disclosed in my prior Patent No, 2,046,910, issued July 7, 1936. It will be understood, however, that the actuators of the mechanical type of tuner, as the term is used herein, are not limited to constructions in which the actuators are necessarily manually moved.

The general object of the present invention is to provide an improved form of mechanical tuner which is cheap to manufacture, rugged in construction, and which is smooth and easy, as Well as precise in operation.

Another object of the invention is to provide 'a mechanical tuner embodying a novel form of station selecting cam and cooperating actuator-of such character that a substantially constant force is utilized in moving the cam to tuning position thereby avoiding inadvertent shifting of the cam on its support as distinguished from the action in some forms of mechanical tuners heretofore proposed in which a decreasing force is required to move the cam with the result that an excessive force is actually applied at the end portion of its path of travel so that it is severely jarred vide a mechanical tuner embodying a novel form of station selector actuator and associated cam by means of which the cam can be'moved exactly to its station tuning posit-ion with a high degree of accuracy.

The invention also resides in various structural improvements in the arrangement for adjustably securing the cams in position on their associated supporting shaft.-

Further objects and advantages of the invention will become apparent as the following description proceeds taken in connection with the accompanying drawings in which:

Figure -1 is a perspective View of a mechanical tuner embodying the present invention;

Fig. -2 is a transverse sectional viewalong the line 2-2 in Fig. 1;

Fig. 3 is a plan view of the tuner unit of Fig. 1;

Fig. 4 is an enlarged detail perspective view of a portion of the unit frame structure;

Fig. 5 is a diagrammatic View illustrating the range of positions of the cams with respect to the associated actuators;

Figs. 6 to 9 inclusive are diagrammatic views representing the various positions. of the selector cams and associated actuators in the course of the tuning operation;

Figs. 10 and 11 are enlarged detail end elevations of one of the cams and its assoicated actuator; i i I Fig. '12 is a detail perspective view of one of the selector cams illustrating particularly the means by which it is adjustably secured to its supporting shaft;

Fig. 13 is an enlarged detail longitudinal sectional View of one of the cams with the associated parts by which it is attached to the Supporting shaft;

Fig. 14 is an enlarged detail perspectiveview of an anchor plate included in the cam supporting structure;

Fig. 15 is an enlarged detail view of one of the wire springs included in the cam supporting structure.

Referring more particularly to the drawings the invention has been shown herein as embodied in a mechanical station selector type tuner unit (Fig. 1) adapted to be incorporated in a radio receiver Within any suitable type of cabinet or housing. Such units are ordinarily supplied to or made by radio set manufacturers and are built intothe set during the course of itsconstruction, although in some instances the tuner may be housed in a separate cabinet and connected to acomplete receiver. The improved tuner here- 1 in illustratedis arranged to rotate a shaft of a movable tuning element of a radio receiver such as an oscillatable variable condenser (not shown). In general the tuner rotates the shaft III to any selected one of a predetermined series of positions of angular adjustment in which the receiver is conditioned for'the reception of radio signals from a corresponding series of broadcast- 1 ing stations. A separate actuatorjis provided for obtaining each tuning position. These actuators i are shown herein as being of the manually operable type and as including axially slidable actuator bars I I carrying push buttons I2, although it will be understood that if desired, actuating i trollable at a distance.

means other than manual push buttons may be provided such, for example, a's' s'olenoids con Upon depressing any selected one of a series of push buttons 12 the 1 tuning element shaft I0 is rotated, through the 1 medium of a novel form of cam selector mechanism hereinafter described, to the corresponding tuningposition. Indicia may be provided on the 5 faces of the push buttons I2 to show the particular stations for which each of them is adapted 1 to tune the assoicated radio receiver.

- Since the tuner unit illustrated is, designed'to 1 be mounted within an enclosing cabinet with the 1 push buttons l2 projecting through a suitable front covering panel (not shown the supporting structure for the unit itself may be simply an un- I ornamented open-type framework or chassis. ,In

the illustrative embodiment this framework in section (Figs. 2 and 4). cured to the opposite ends of the channel l4 by suitable lugs I5. The particular lug construction shown forms no part of the present invention but I is described more particularly and claimedin my copending application Serial No.; 209,251, filed 5 May 21, 1938. The actuator bars ,Il areslidably supported for endwise movement in alined 3 apertures l6 and I1 formed respectively in the 1 front and rear legs of thechannel M.

An oscillatable member or tuner shaft I9 is 1 oscillate through an arc of substantially less than i 5 180.

Accordingly, a speed reduction connection is preferably provided between the shafts l0 and I9. This connection has been shown in the form of a pair of pulleys 20 and 2| fixed on the respective shafts and connected by an endless belt .22. The ratio of diameters of the pulleys 1 may, for example, be three to four'so that the 3 shaft I9 will move through an arc of only 135 1 1 while the shaft I0 is moving through an arc of 180.

In some instances it is desirable tOnPI'O- 1 cludes a pair of sheet metal end plates 13 joined i by a sheet metal channel I4 of U-shaped cross- I The plates I3are sevid e means in the tuner .unit itself for positively g limiting the-arc of movement of the tuner shaft I9 rather than depending merelyupon thelimits 1 of movement for the condenser, attached to'the 1 shaft I 0 and for this purpose stop pins 23 may be i secured to the pulley 2| at suitably spaced points for-the angle of movement desired and arranged to abut-against a fixed stop pin 24.

A iSQIiGS of flat peripheral cams, designated ing extremity of its range of adjustment.

generally by the numeral 25 (Fig. 2) are car ried by the tuner shaft I9. One cam is provided for each station selector push button l2. Each of these cams 25 is eccentrically mounted on the shaft i9 and is adjustable about its axis so that the major axis 26 of each of the generally rectangular cams 25 (Fig. 5) can be displaced, from one extremity of a predetermined range of adjustment, an arcuate distance bearinga predetermined ratio to the displacement of the radio receiver tuning element, necessary to accomplish tuning of the receiver for the reception of signals from the station which the particular cam represents. The predetermined ratio is the same as the ratio of speeds of the shafts I0 and I9. For example, if the radio receiver condenser must be displaced 60 from one extremity of a range of movement of 180 in order to tune the receiver for signals from a station A, then the corresponding selector cam 25 is adjusted to a position in which it-is displaced three-fourths of 60 or, in other words, 45 from the correspond- This calculation is made on the basis of a three to four ratio of speeds for the shafts I0 and I9 as described. In the event that a special condenser is used having a range of adjustment of only say 135, then of course the ratio noted may be made one to one and the tuner shaft connected directly to the condenser shaft.

Upon reference to Fig. 2 it will be seen that the cams 25 are arranged in a generally fan.- like configuration about the axis of the shaft 19. If. the range of movement of the shaft I9 is 135, then the range of adjustment of the cams 25 is also 135. Accordingly, the extreme positions which the major axis 26 of the cams 25 can occupy, either by virtue of adjustment or oscillation of the shaft l9, lies within an arc of 270 (see Fig. 5). This has been found to be a desirable range of movement for practical operation.

It'is small enough to insure positive actuation of the cams by the actuators, and yet great enough to allow a large range for accurate positioning of the cams. As tothe latter point, it is desirable to have the range of adjustment as; nearly as great as the range of movement of "the condenser as is possible since any error in positioning the cams will be multiplied in positioning the condenser by the radio between their ranges of movement. No implication is intended by the term fan-like, as applied to the cam arrangement, that the cams must be disposed at progressively different angles as shown in Fig. 2.

posed for movement along a line which bisects the angular area lying outside the 270 range of positions for the cams (Fig. 5) The actuators ii are preferably fashioned as stampings from sheet metal and each of them is provided with a fork-shaped inner end including laterally spaced longitudinal upper and lower projections 21 and 28 located on opposite sides of the axis o f1rotation of the cams 25. These forkedactuatorsare dimensioned to embrace the butt ends ofthe cams 25 and are located-generally opposite such end portions rather than opposite the elongated outer end portions. The actuatorsare -of the fork-shaped actuators ,shapedj actuators are dimensioned to embrace -the-buttends of the cams and as the cams move yieldablyrretained in their retracted positions (Fig.2) .iby helical tension springs I I! disposed in suitable recesses in the actuatorsand anchoredattheir opposite ends to the respective actuators and to the front leg of channel M. The guide apertures l] in the channel. are enlarged attheir-centers to permit free passage of thesprings (Fig. 4).

In the .operation of the tuner the one'of the actuators. Il,..corresponding-.to the station selected,v is pushed inwardly. If the. one of;.the scams 25 associated with .the selected actuator is, for example, located above its mid-line position (Fig. 6)..the.. upper actuator projection 21 strikes the cam and causes it to rotate in a counter-clockwise direction until it reaches its predetermined tuning position shown in Fig. 8. Similarly, if the selectedone of thecams 25 is, at the time of movement of its associated actuaton. located below the center-line of the path of the actuator,. the second or lower projection, 28 on the actuator (Fig. '7) strikes the cam, so .that it is oscillated in a clockwise direc tion to the predetermined position of Fig. 8. In this Waythe cams 25 may be selectively moved to .a .predeterminedsposition to tune in the corresponding station irrespective of the direction or extent oftheir displacement from thisposition at the .time they are contacted by the actuator. It will also be vnotedthat the length of stroke of. the actuator is always constant. As

soon as. the actuator has been pushed fully in tocomplete rotation of the cam it :may be reactuatorsneed not be locked or retained in engagement with the cams. I

For the actuators II .to be able to rotate the cams25 as described above it is necessary, as

.Willbe seen from an inspectionof Figs. 6 and 7, that the cams should-:be displaced at least somelittle distance above or-below the path of .the actuator at the. point of initial contact therebetween. Otherwise if the elongated end of thecam is facing directly toward the actueator in a dead center positionv the actuator will be ineffective to move the cam. For that reason the range of possible positions for the cams .must be limited to substantially less than 360 in the manner described ,above, and preferably the range should besubstantially Z'lO for best practical operation.

Precision of location of the cams, 25 in their final tuning position is insured by the camming action of complemental abutting surfaces formed on the actuators H and the cams 25. In

the preferred construction illustrated, fiat surfaces-29 are machined on thebutt end portions of the cams and are disposed to fit snugly against .complementaLflat surfaces 29 on the bottom Walls of the recesses formed in the forward ends II. I The forkinto, their final tuning positions, the flat surfaces 29? on the actuators come into contactwith the lower outer corners of the cams .and push the .camsinto' their final position. The complemental fiat surfaces:29. and 29inch be machined to ntwithsmcetyand 'at'small expense so that very preciseflocation .of the selector cams in their final tuning positions-isachieved.

r .In orderto-insure-smooth and .easy operation of then-tuner upon-the -application .of a uniform force to theactuatorsull throughout their working strokes a special shape for the selector cams -25 is preferably utilized. :For this purpose recesses are formedssin I the side .edges of the cams so as rto provide curved shoulders thereon facing generally. toward the butt ends :ofv the .cams. Theseishoulders .3f0...are..so dimensioned or 10- cated'zon the sides ofthezcams. that'ithey will be contactedcfby onefor (the other of the actuator projections fl or .28.as the cams .move through the last 90 of. their oscillatory movement and before reaching their i'fina'l'tuning position. The contourmf, the.:.cam.edges described prevents any jamming ofthe actuators against the cams during the final 90; of zcammovement since the pr'ojections'fl or..28,-i.rabutting against the shoulders. 3.0, apply a 'rotative force thereto in a line ofaction highlyeffective to causerotation. The ends of the projections 21 and 28 are slightly rounded ionstheir :active edges .to further insure smooth 'slidingmotion. As aresult, a substantially constant force is required to move the cams throughout-the working strokes of the actuators. I v

The constant force-type-of operation described I above is to :be distinguished from that resulting from the use of other types of cams such, for example, as heart-.shapedrcams rotated by a roller type .actuator' which engages the cam periphery and nna'lly'enters. the recess in the "throughout the actuator stroke. The applica-' tion of an 'excessiveiforceatthe completion of the stroke tends, however; to jar and dislodge the cams and spoil their adjustment on their supporting shaft so that they quickly become misalined. In the improved construction herein disclosed, such inadvertent jarring of the selector cam parts is entirely obviated.

An adjustable :connection is preferably pro vided betwee'n the selector cams 25 and their supporting member orshaft l9 so that the cams.

can readily be shifted to definite angular positions about 'ithe shaft for initially adjusting or readjus'tingthe' tuner for a predetermined list of stations. For this purpose the cams 25 are frictionally mounted on theshaft H], the cams being provided with notches 3| in their butt ends which embrace the shaft. The sidesof these notches are taperedas; for example, with a taper of about 2?. sothatjthe cams will wedgingly engage the shaft. A pair of generally U or hairpin-shaped resilient wire springs 32 yieldably urge each of the cams into such wedging engagement with the shaft. These wire springs are disposed. on opposite sides of each cam and the base portions thereof are seated-in peripheral annular grooves 33. formed in the shaft on. each side of the respective cams .(Fig. 13). The legs of the U shaped wire.;springs 32 are bowed out somewhat and their zbent ends are hooked over 1 ears. 35- formedat the zfourrllcorners of; small lreca 1 tangul-arxsheet imetal-z anchor: plates 53.4 21(Figs; 12 ,1 and 1 D "1 positioned *on ifih couterr ends of each of v 5 the cams 25. Eachio'f thes'er platsris held" in posie '1 tion onithe :end ofzthelassociated icamlbyia centrally located 5362 struck outsjromethe: plate and'fitt'ing; imazcomplemental' ecess 'nthewcam end-surface; 1 vIn Eadjustingi 'the"icams--25;initial1 selected list 0f;='S'l3atiOns,-G1 theapparatus discl'osed'f6 thezxoperatorlto :have 1 1 access to'thei interion ofjth uniaaiAlL'ofthe ad+ justment manipulations-tcanaibeicarriediout very i simply and.easily,;-.ev.en an unskilled operator, from the exterior; of ithe; device: v'lh'ere. are; :but

two steps in the; operation. L'First, the; operator depresses a selectedpushsbutton thereby rotating s; not ;nec'essary, ;-with or some the associated camfun'tilei itsi;tuning p.osi.-

tion (Figf'. '8) a .-Ihstead-, ;of .releas'ing'icthe push 1 'button,vvhowe'ver; aszimfche normal tuningiopere ation,'fthe;.operator: retains: the push button depressed and furthermore forces-it inwardly: with 'more'thanthe usualpressure required; As are.- I sult, theilegs-ofthe resilienti'wire 'SDliIlESf3Z'i2118 1 straightenedout and thez-camfiisydislodged from thenshaft. and moved a: short distanceiradially away from it althoughstill retained'iagainstrm tation 'by the actuator forknwhich embracesi the butt of the'cam. The extent of radial-displace 1 l ment of the cam is'limited by the contactzofathe shaft I9 against the. bottom of' a complemental 1 notch'29 iformed inithe forward; face of .theactuator :so th'atithe springstzwillxnot be. stressed beyond their :elasticrlir'nit and thus :be permanent.-

1y deformed. I 1With i-the" selected. cam thusreleased frometheshaft;:.leaandi'heldaagainst rotationwith-respect toitythe second step inthe adjustment operationis carriedaout; This second 'step consists simply ofilrotatingthe. shaft-.19

manuallyuntil the sel'ected broadcasting station has been .tuned-iniontthe' associated radio. re,-

ceiver. When the tunerashaft has been-rotated to .such point thefiselected actuator :is released positioned for thereaftentuningin the newly se- 1 and the displaced cams snaps :backinto vwedging 'engag'ementjwith theishaftdue to-tthe resiliency '-of1 the 'springs.32. s0: tlmtrthe cam :is precisely repeated .for positioning each of the-variousselector cams for a: corresponding series of station tuning positions: ,-After having once vbeen initially adjusted in this mannerpit is only; necessary for the operator to depress lithe push-button correspending to .a jselectedustation in order; :to tune 'theradio receiven fora-thev reception of signals fromiathat. station n" the -manner heretofore describedai i Although: a .particulanembodimentg of' the *vention has. been; shown and "describediin; some detail for purposeswof explanation of its various novelfeaturesg there is no intention to limit the invention thereby to such embodiment but, on the other hand," the 1 appended claims are intended to cover allmodifications and alternative "constructions Within th ii -it"and scope of the inventiorhfl I claim as my invention. .1

19A mechanical station selector type tuner: for a"'radio'rece1ve'r comprising, i'n c0mbination;

an' actuator movable generally" rectilinearly and recessfin it s' forward"end'bordered by rti'ons on opposite flat periphaacoaao tionsiof'gsaid actuator; means for-supporting said Team .:;for oscillation i--in=: said-plan about an axis longitudinally: eccentric .'.to the center of said elongated came and transverse to thepath of movementipf; said actuator. and with the outer,- most: end .ofxsaid cam facing'generally away from saidactuator and never directly toward the same,

means for connecting saidacam in ;driving;r'e1a tion iWith a tuningselem'ent. of a radio receiver, I

and vmeans for imoving'saidactuator toward said camtowcause .said projecting iportions of s'aid actuator sto contact alternative adjacent edges of:said.cam:and push theisamearound to a 'pre determined position .in which the'longitudinal axis of said elongated'cam-projects awayfrom said actuator .inisubstantial .alinement therewith, said-cam; beingprovided with inset shoulderson opposite side edges thereof facing I generally towardthe .butt end of said camand dimensioned tobep-contacted ,by said projecting actuator por tlons to prevent jamming of the actuato ragai'nst the cam as theo-latter-is pushed through the last 90?;of its rotation toward said predetermined p0 same, means for connecting said cam in driving relation with aituning element of "a radio 'receiver, and means for'moving saidactuatorto- Ward;sa1d' cam to -cause. said projecting arms of .saidactuator: to contact alternativeadjacent edges of said cam and push thevsar'ne around-to aupredetermined position in which the longitudinalaxis vofisaidelo-ngated cam projects away from said actuator in substantial alinement therewithg-"saidt camiloeing provided with curved inset 'sshou'lders on opposite sides thereof facing generally toward the butt of the cam and diimensioned to be contactedby said projecting actuator arms-to prevent jammi-n'g of the acv tuatoragainstlfthe cam as the-latter is pushed through the l'ast '90 of: its :rotation toward said predetermined position from eithersi'de thereof,

said recess in said actuator-being dimensioned to embrace the butt end of 'said' cam when the latter is in-said predetermined position, the bot- I tom of said recess and said butt end'of said cam being provided with complemental surfaces for locating said" cam precisely in said predetermined position; I r

station fselector tuner mechanism "coni- -pr1s1ng;:in conibination, a rotatable shaft adapted-fto -be connected to' a radio receiver tuning element; a plurality of station selector cams disposed side by "side along said shaft and projecting-radially therefrom at"v a'rious angles corresponding to different station tuning positions of complemental series of actuators selectively enlga i llgle with "sai cams for rotating the same to predetermined tuning positions, and means T r v fc'ir fitili'zingsaidactuators to'adjust the angular r ecting p'or- "positions" of said cams on said shaft,f said last the'receive'r tuning'element, means including a for a I named means including means for yieldably holding said cams in position on said shaft by applying a biasing force thereto radially of the.

shaft and in a direction to be in alinement with the lines of action of said actuators when said cams are in said predetermined position, whereby said actuators may be utilized to oppose and overcome said biasing force to release said holding means and permit manual rotation of said shaft with respect to selected ones of said cams.

4. A station selector type tuner mechanism comprising, in combination, a rotatable shaft adapted to be connected to a radio receiver tuning element, a plurality of elongated peripheral station selector cams projecting radially from said shaft within an arc of substantially less than 180, each of said cams being provided With a tapered notch in the butt end thereof embracing said shaft, means for yieldably urging each of said cams toward said shaft into wedging engagement therewith for holding said cams in selected positions of angular adjustment about the shaft axis corresponding to various station tuning positions of the receiver element, and means including a complemental series of actuators engageable selectively with said cams for not only rotating the cams to a predetermined tuning position but for also engaging the butt ends thereof and forcing said cams away from said shaft to release said wedging engagement and permit manual rotation of said shaft while holding said cams against rotation to thereby adjust the angular positions of said cams on said shaft, said actuators having recessed forward ends dimensioned to receive the butt ends of said cams when the latter are in tuning position.

5. A station selector type tuner mechanism comprising, in combination, a rotatable shaft adapted to be connected to a radio receiver tuning element, a plurality of elongated peripheral station selector cams projecting radially from said shaft within an arc of substantially less than 180, each of said cams being provided with a tapered notch in the butt end thereof embracing said shaft, means including a spring for yieldably urging each of said cams toward said shaft into Wedging engagement therewith for holding said cams in selected positions of angular adjustment about the shaft axis corresponding to various station tuning positions of the receiver element, and means including a complemental series of actuators engageable selectively With said cams for not only rotating'the cams to a predetermined tuning position but for also engaging the butt ends thereof and forcing said cams away from said shaft to release said Wedging engagement and permit manual rotation of said shaft while holding said cams against rotation to thereby adjust the angular positions of said cams on said shaft, said actuators having recessed forward ends dimensioned to receive the butt ends of said cams when the latter are in tuning position, the base portions of said actuator recesses being dimensioned to engage said shaft at the end of a predetermined movement of said actuators toward the same to thereby limit the extent of displacement of said cams from said shaft and the strain placed upon said springs.

6. A station selector tuner mechanism comprising, in combination, a rotatable shaft adapted to be connected to a tuning element of a radio receiver, a generally flat peripheral station selector cam disposed transversely with respect to said shaft, said cam having a tapered notch in one edge thereof embracing said shaft, said shaft having annular grooves in the surface thereof on each side of the shaft, and means including resilient U-shaped wire springs fitted in said grooves and extending along the opposite sides of. said cam with the outer ends of the arms thereof releasably secured to said cam for yieldably urging said cam into wedglng engagement With said shaft, wherebysaid cam may be disposed in any selected position of angular adjustment about the shaft axis.

EDWARD L. BARRETT. 

